Resource allocation method, identification method, base station, mobile station, and program

ABSTRACT

Provided is a technique capable of reporting resource block allocation information with no waste when an allocated resource block is reported, because in the current LTE downlink, the waste of the amount of resource allocation information increases in some cases since a restriction is imposed such that 37-bit fixed scheduling information is transmitted. A resource block group consisting of at least one or more resource blocks continuous on the frequency axis is allocated to a terminal, and the number of controlling signals for reporting allocation information indicating the allocated resource blocks is determined.

TECHNICAL FIELD

The present invention relates to a technique for mobile wireless systems, and particularly, to a technique for resource allocation.

BACKGROUND ART

For uplink according to LTE (Long Term Evolution) in 3GPP (3^(rd) Generation Partnership Project), an SC (single-carrier)-FDMA (Frequency Division Multiple Access) scheme is adopted for a wireless access scheme to avoid an increase in PAPR (Peak to Average Power Ratio) and achieve wide coverage. According to SC-FDMA, one frequency block can be allocated per mobile station within one Transmit Time Interval (TTI), where a frequency block is composed of at least one or more resource blocks (RBs: each composed of a plurality of sub-carriers) that are consecutive on a frequency axis. For a small number of frequency blocks as in SC-FDMA, a Tree-Based (see Non-patent Document 1) method can minimize the amount of information on resource allocation. Accordingly, the Tree-Based method is employed in notification of uplink resource allocation information (Uplink Scheduling Grant) in scheduling for LTE uplink.

Non-patent Document 1: 3GPP R1-070881, NEC Group, NTT DoCoMo, “Uplink Resource Allocation for E-UTRA,” February 2007.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

On the other hand, in OFDM (Orthogonal Frequency Division Multiplexing) adopted in an LTE downlink access scheme, discontinuous sub-carrier allocation is made to increase the number of frequency blocks and an additional multi-diversity effect can be achieved to improve throughput. In OFDM, adoption of a Bit Map method (a method suitable for a larger number of frequency blocks) is currently being studied in notification of resource block allocation information in LTE downlink (Downlink Scheduling Grant). The Bit Map method has a greater overhead than in the Tree-Based method used in notification of LTE uplink RB allocation information (Uplink Scheduling Grant).

In particular, when using the Bit Map method, resource block allocation of 100 RBs requires 100-bit resource block allocation information regardless of the number of frequency blocks. On the other hand, when using the Tree-Based method, Scheduling Grant having log₂ 100(100+1)/2=13 bits is notified for one frequency block via PDCCH (Physical Downlink Control Channel), which is a downlink control signal, from a base station to a mobile station.

In Uplink Scheduling Grant according to current LTE, it is possible to notify allocation information on only one frequency block. In LTE downlink, limitation is posed on a resource block to be allocated and resource block allocation information of 37 bits at maximum can be transmitted; when resource block allocation information has a size within 37 bits, dummy data is inserted. Thus, it is necessary to always reserve a resource such that information of 37 bits can be transmitted in one piece of Uplink Scheduling Grant. However, for example, in a case that two frequency blocks are allocated among 100 RBs to a terminal, and resource block allocation information, which is information representing the allocation, is to be transmitted in accordance with the Tree Based method, only 13 bits×2=26 bits are required; however, dummy data of 11 bits is inserted for notification, which is inefficient. Thus, in some cases, the amount of useless resource allocation information may be increased.

It is therefore a problem to be solved by the present invention is to provide a technique capable of, in notifying an allocated resource block, notifying resource block allocation information without inefficiency.

Means for Solving the Problems

The present invention for solving the aforementioned problem is a resource allocation method, characterized in comprising: allocating resource block groups including at least one or more resource blocks consecutive on a frequency axis to a terminal; and determining a number of control signals for notifying allocation information representing resource blocks in said allocated resource block groups.

The present invention for solving the aforementioned problem is a communication method of allocating resource block groups including at least one or more resource blocks consecutive on a frequency axis, characterized in comprising identifying resource blocks allocated to a mobile station from information on allocated resource block groups notified using a determined number of control signals.

The present invention for solving the aforementioned problem is a wireless system, characterized in comprising: allocating means for allocating resource block groups including at least one or more resource blocks consecutive on a frequency axis to a terminal; and determining means for determining a number of control signals for notifying allocation information representing resource blocks in said allocated resource block groups.

The present invention for solving the aforementioned problem is a wireless system for allocating resource block groups including at least one or more resource blocks consecutive on a frequency axis, characterized in comprising identifying means for identifying resource blocks allocated to a mobile station from information on allocated resource block groups notified using a determined number of control signals.

The present invention for solving the aforementioned problem is a base station, characterized in comprising: allocating means for allocating resource block groups including at least one or more resource blocks consecutive on a frequency axis to a terminal; and determining means for determining a number of control signals for notifying allocation information representing resource blocks in said allocated resource block groups.

The present invention for solving the aforementioned problem is a mobile station for identifying allocation of resource block groups including at least one or more resource blocks consecutive on a frequency axis, characterized in comprising identifying means for identifying resource blocks allocated to the mobile station from information on allocated resource block groups notified using a determined number of control signals.

The present invention for solving the aforementioned problem is a program for a base station, said program being characterized in causing said base station to execute: allocating processing of allocating resource block groups including at least one or more resource blocks consecutive on a frequency axis to a terminal; and determining processing of determining a number of control signals for notifying allocation information representing resource blocks in said allocated resource block groups.

The present invention for solving the aforementioned problem is a program for a mobile station for identifying allocation of resource block groups including at least one or more resource blocks consecutive on a frequency axis, said program being characterized in causing said mobile station to execute identifying processing of identifying resource blocks allocated to the mobile station from information on allocated resource block groups notified using a determined number of control signals.

EFFECTS OF THE INVENTION

According to the present invention, inefficiency in resources encountered in notifying allocation information can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

[FIG. 1] A diagram for explaining frequency blocks.

[FIG. 2] A block diagram of a base station in a wireless communication system in a first embodiment.

[FIG. 3] A block diagram of a mobile station in the wireless communication system in the first embodiment.

[FIG. 4] A flow chart of the first embodiment.

[FIG. 5] Another block diagram of a base station in the wireless communication system in the first embodiment.

[FIG. 6] Another block diagram of a mobile station in the wireless communication system in the first embodiment.

[FIG. 7] Still another block diagram of a base station in the wireless communication system in the first embodiment.

[FIG. 8] Still another block diagram of a mobile station in the wireless communication system in the first embodiment.

[FIG. 9] Yet still another block diagram of a base station in the wireless communication system in the first embodiment.

[FIG. 10] Yet still another block diagram of a mobile station in the wireless communication system in the first embodiment.

[FIG. 11] A flow chart of a second embodiment.

[FIG. 12] An example of a correspondence table for a frequency block and an allocation resolution.

[FIG. 13] A diagram showing an example of RBs allocated to a mobile station.

[FIG. 14] A diagram showing an example of RBs allocated to UE1 and UL Scheduling Grant.

[FIG. 15] A diagram showing an example of RBs allocated to UE2 and UL Scheduling Grant.

[FIG. 16] A diagram showing an example of an RB allocated to UE3 and UL Scheduling Grant.

[FIG. 17] A diagram showing an example of an RB allocated to UE4 and UL Scheduling Grant.

[FIG. 18] A diagram for explaining the Tree-Based method modified in accordance with an allocation resolution.

[FIG. 19] A flow chart of a third embodiment.

[FIG. 20] A diagram showing the number of bits of resource allocation information with respect to the maximum frequency blocks and an allocation resolution.

EXPLANATION OF SYMBOLS

-   100 Base station -   101 Receiver -   102 Uplink RS separator -   103 Uplink CQI measurement section -   104 Uplink scheduler -   105 Maximum-number-of-frequency-blocks determining section -   106 Uplink data signal separator -   107 Uplink data signal demodulator -   108 Uplink control signal separator -   109 Uplink control signal demodulator -   110 Downlink scheduler -   111 Downlink control signal generator -   112 Downlink RS signal generator -   113 Downlink data signal generator -   114 Multiplexer -   115 Transmitter -   116 UE ID generator -   200 Mobile station -   201 Receiver -   202 Downlink RS separator -   203 Downlink CQI measurement section -   204 Downlink data signal separator -   205 Downlink data signal demodulator -   206 Downlink control signal separator -   207 Downlink control signal demodulator -   208 Downlink scheduling information extracting section -   209 Maximum-number-of-frequency-blocks extracting section -   210 Uplink scheduling information extracting section -   211 Uplink control signal generator -   212 Uplink RS signal generator -   213 Uplink data signal generator -   214 Multiplexer -   215 Transmitter

BEST MODES FOR CARRYING OUT THE INVENTION

According to Long Term Evolution (LTE) being currently standardized in the 3^(rd) Generation Partnership Project (3GPP), Orthogonal Frequency Division Multiplexing (OFDM) is adopted for a downlink access scheme. The frequency domain channel dependent scheduling is applied to LTE downlink, and a plurality of frequency blocks can be allocated per mobile station within one Transmit Time Interval (TTI), where a frequency block is a resource block group composed of at least one or more resource blocks (RBs: each of which is composed of a plurality of sub-carriers) that are consecutive on a frequency axis. FIG. 1 shows an example of frequency block allocation in LTE downlink. This represents a case in which four mobile stations are scheduled within one TTI in a system band. The number of frequency blocks for mobile station 1 (UE1) is three, the number of frequency blocks for mobile station 2 (UE2) is two, the frequency block for mobile station 3 (UE3) counts one, and the frequency block for mobile station 4 (UE4) counts one.

The present invention is characterized in determining a number of pieces of scheduling information (Uplink Scheduling Grant), which is information on resource blocks allocated to terminals by a base station for allocating a plurality of frequency blocks to one mobile station as described above, and a number of control signals PDCCH's (Physical Downlink Control Channels) for notifying the scheduling information to terminals, or a number of bits thereof. Now details of the present invention will be described below with reference to the accompanying drawings.

First Embodiment

A block diagram of a base station in this embodiment is shown in FIG. 2, and that of a mobile station in FIG. 3.

First, a configuration of a base station 100 will be described.

A receiver 101 in the base station 100 receives a signal from a mobile station 200, establishes uplink synchronization using a guard interval, and outputs a base station receive signal S_(RXB).

An uplink RS (Reference Signal) separator 102 separates from the base station receive signal S_(RXB) an uplink RS signal S_(URSB) in which uplink RS signals of a plurality of mobile stations are multiplexed, and outputs it.

An uplink CQI measurement section 103 receives the uplink RS signals S_(URSB) for a plurality of mobile stations as input, calculates CQI (Channel Quality Indicator) for each mobile station on an RB-by-RB basis, and outputs it as uplink CQI information S_(UCQB).

An uplink scheduler 104 makes uplink scheduling and resource allocation to a mobile station. The uplink scheduler 104 determines a number of frequency blocks to be allocated to one terminal based on the uplink CQI information S_(UCQB). In particular, it increases the number of frequency blocks for good CQI, and decreases the number for poor CQI. It allocates resource blocks one by one so that the determined number of frequency blocks is attained. It then generates resource allocation information representing positions of allocated RBs in accordance with the Tree Based method for each frequency block, and outputs it as UL Scheduling Grant S_(USCB). That is, a number of pieces of UL Scheduling Grant S_(USCB), which number is equal to the number of frequency blocks for one user, are generated. In allocating 100 RBs, the uplink scheduler 104 generates 13-bit UL Scheduling Grant. While a configuration for generating a number of pieces of UL Scheduling Grant, which number is equal to the number of frequency blocks, will be described hereinbelow, other configurations may be employed. For example, a configuration in which allocation information on a plurality of frequency blocks is written in one piece of UL Scheduling Grant to reduce the number of pieces of UL Scheduling Grant relative to the number of frequency blocks may be contemplated.

A downlink control signal generator 111 receives the UL Scheduling Grant S_(USCB), mobile station identification signal S_(UIDB) and DL Scheduling Grant S_(DSCB) as input, multiplexes the mobile station identification signal S_(UIDB) with each of the plurality of pieces of UL Scheduling Grant and DL Scheduling Grant S_(DSCB), generates a downlink control signal PDCCH S_(DCCB) from each of the plurality of pieces of UL Scheduling Grant, and moreover, generates a downlink control signal PDCCH S_(DCCB) from the DL Scheduling Grant. The downlink control signals PDCCH's S_(DCCB) are generated as the downlink control signal PDCCH S_(DCCB) for the UL Scheduling Grant S_(USCB) and that for the DL Scheduling Grant S_(DSCB). In other words, the downlink control signals PDCCH's S_(DCCB) are generated in a number equal to the sum of the number of pieces of Scheduling Grant including the UL Scheduling Grant S_(USCB) and DL Scheduling Grant S_(DSCB). The downlink control signal PDCCH S_(DCCB) is multiplexed with information bits indicating a DCI (Downlink Control Information) format, which is an identifier for distinguishing between the UL Scheduling Grant and DL Scheduling Grant. For example, a DCI format of zero is multiplexed for UL Scheduling Grant and of one for DL Scheduling Grant in the downlink control signal PDCCH S_(DCCB).

A downlink RS signal generator 112 generates a downlink RS signal and outputs it as a downlink RS signal S_(DRSB).

A downlink data signal generator 113 receives the DL Scheduling Grant S_(DSCB) as input, multiplexes downlink data signals from a plurality of mobile stations in accordance with an RB pattern indicated by the DL Scheduling Grant S_(DSCB), generates Physical Downlink Shared Channel (PDSCH) S_(DDCB), and outputs it.

A multiplexer 114 receives the PDCCH S_(DCCB), RS signal S_(DRSB) and PDSCH S_(DDCB) as input, multiplexes these signals to generate a multiplexed downlink signal S_(MUXB), and outputs it.

A transmitter 115 receives the multiplexed downlink signal S_(MUXB) as input, generates a transmit signal S_(TXB), and outputs it.

An uplink data signal separator 106 receives the base station receive signal S_(RXB) as input, extracts therefrom Physical Uplink Shared Channel (PUSCH) S_(UDCB) in which uplink data signals from a plurality of mobile stations are multiplexed, and outputs it. An uplink data signal demodulator is supplied with the PUSCH S_(UDCB) as input, and demodulates it to reproduce mobile station transmitted data.

An uplink control signal separator 108 receives the base station receive signal S_(RXB) as input, extracts therefrom Physical Uplink Control Channel (PUCCH) S_(UCCB) in which uplink control signals from a plurality of mobile stations are multiplexed, and outputs it. An uplink control signal demodulator 109 demodulates the PUCCH S_(UCCB), and outputs a downlink CQI measurement signal S_(DCQB), which is a result of measurement of downlink CQI transmitted by a plurality of mobile stations. A downlink scheduler 110 receives the downlink CQI measurement signal S_(DCQB) as input, makes downlink scheduling for a plurality of mobile stations, generates DL Scheduling Grant S_(DSCD), which represents information on allocated RBs, and outputs it.

A UE ID generator 116 generates mobile station identification information S_(UIDB), and outputs it.

Subsequently, a mobile station will be described. FIG. 3 is a block diagram showing a main configuration of a mobile station in this embodiment.

A receiver 201 in a mobile station 200 receives a signal from the base station 100, establishes downlink synchronization using a guard interval, and outputs a mobile station receive signal S_(RXU).

A downlink RS (Reference Signal) separator 202 receives the mobile station receive signal S_(RXU) as input, separates therefrom a downlink RS signal S_(DRSU) in which downlink RS signals are multiplexed, and outputs it. A downlink CQI measurement section 203 receives the downlink RS signal S_(DRSU) as input, calculates CQI on an RB-by-RB basis, and outputs it as downlink CQI information S_(DCQB).

A downlink control signal separator 206 receives the mobile station receive signal S_(RXU) as input, separates therefrom PDCCH S_(DCCU) in which downlink control signals from a plurality of mobile stations are multiplexed, and outputs it.

A downlink control signal demodulator 207 receives the PDCCH S_(DCCU) as input, demodulates it to reproduce a downlink control signal, separates therefrom all of results of reproduction in which the mobile station identification information corresponding to the mobile station itself is multiplexed, and outputs it as a reproduced downlink control signal S_(DCMU). It should be noted that the PDCCH's for the mobile station itself are multiplexed in a number equal to the number of frequency blocks. The downlink control signal demodulator 207 also checks a result of demodulation of the PDCCH S_(DCCU) and reproduction of the downlink control signal as to whether there is found an error in all downlink control signals destined to the mobile station itself, in a case that no error is found in any PDCCH, generates a signal indicating ACK as a downlink control signal decision signal S_(DAKU), or in a case that any error is found there, similarly generates a signal indicating NACK, and outputs it. It should be noted that the downlink control signal decision signal S_(DAKU) is notified from the mobile station 200 to the base station 100, and in a case that the downlink control signal decision signal S_(DAKU) is NACK, the base station 100 retransmits all downlink control signals corresponding to the mobile station 200. While one downlink control signal decision signal S_(DAKU) is generated for all PDCCH'S transmitted to one user, it may be contemplated to generate respective downlink control signal decision signals S_(DAKU) for the PDCCH's. In a case that a downlink control signal decision signal S_(DAKU) is generated for each PDCCH, the base station 100 can retransmit an erroneous PDCCH.

A downlink scheduling information extracting section 208 receives the reproduced downlink control signal S_(DCMU) as input, and extracts information bearing “1” in its DCI format, that is, extracts downlink resource allocation information DL Scheduling Grant. It then identifies an RB represented by the downlink RB allocation information contained in the DL Scheduling Grant, and outputs it as downlink RB allocation decision information S_(DSCU).

An uplink scheduling information extracting section 210 extracts, from the reproduced downlink control signal S_(DCMU), information bearing “0” in its DCI format, that is, extracts UL Scheduling Grant representing information on allocated uplink RBs. Next, it identifies an RB represented by the uplink RB allocation information contained in the UL Scheduling Grant, and outputs it as uplink RB allocation decision information S_(USCU).

An uplink control signal generator 211 receives the uplink RB allocation decision information

S_(USCU) and downlink CQI information S_(DCQB) as input, generates Physical Uplink Control Channel (PUCCH) S_(UCCU) in which the downlink CQI information S_(DCQB) is multiplexed with a predetermined resource for a control signal indicated by the uplink RB allocation decision information S_(USCU), and outputs it.

An uplink RS signal generator 212 receives the uplink RB allocation decision information S_(USCU) as input, generates an uplink RS transmit signal S_(USCU) using a resource for RS predetermined in the uplink RB allocation decision information S_(USCU), and outputs it.

An uplink data signal generator 213 receives the uplink RB allocation decision information S_(USCU) as input, generates Physical Uplink Shared Channel (PUSCH) S_(UDCU) using a resource for a data signal predetermined in the uplink RB allocation decision information S_(USCU), and outputs it.

A multiplexer 214 receives the PUCCH S_(UCCU), uplink RS transmit signal S_(URSU), PUSCH S_(USCU) and downlink control signal decision signal S_(DAKU) as input, multiplexes these signals to generate a multiplexed mobile station signal S_(MUXU), and outputs it. A transmitter 215 receives the multiplexed mobile station signal S_(MUXU) as input, generates a mobile station transmit signal S_(TXU), and transmits it to the base station 100.

A downlink data signal separator 204 receives the downlink RB allocation receive signal S_(DSCU) and mobile station receive signal S_(RXU) as input, separates therefrom PDSCH S_(DDCU) multiplexed with the downlink RB allocated to the mobile station itself based on the downlink RB allocation decision information S_(DSCU), and outputs it. A downlink data signal demodulator 205 receives the PDSCH S_(DDCU) as input, demodulates it to reproduce transmitted data from the base station to the mobile station itself.

Subsequently, an operation of this embodiment will be described with reference to a flow chart in FIG. 4. The following description will be made with reference to a case in which 100 RBs are allocated.

The receiver 101 in the base station 100 receives a signal from the mobile station 200, establishes uplink synchronization using a guard interval, and outputs a base station receive signal S_(RXB) (Step S1).

The uplink RS (Reference Signal) separator 102 separates from the output base station receive signal S_(RXB) an uplink RS signal S_(URSB) in which uplink RS signals from a plurality of mobile stations are multiplexed, and outputs it (Step S2).

From the uplink RS signals S_(URSB) for a plurality of mobile stations, the uplink CQI measurement section 103 calculates CQI (Channel Quality Indicator) for each mobile station on an RB-by-RB basis, and outputs it as uplink CQI information S_(UCQB) (Step S3).

The uplink scheduler 104 determines a number of frequency blocks for resources to be allocated to each mobile station based on the uplink CQI information S_(UCQB) for each mobile station (Step S4).

RBs are allocated so that the determined number of frequency blocks is attained (Step S5).

Next, the uplink scheduler 104 generates information representing positions of the allocated RBs for each frequency block, and outputs it as a number of pieces of UL Scheduling Grant S_(USCB) each having 13 bits, which number is equal to the number of frequency blocks (Step S6).

The downlink control signal generator 111 is supplied with the UL Scheduling Grant S_(USCB), DL Scheduling Grant S_(USCB) and mobile station identification information S_(UIDB) as input, multiplexes the mobile station identification information S_(UIDB) with each of the plurality of pieces of UL Scheduling Grant S_(USCB) and DL Scheduling Grant S_(DSCB), generates downlink control signals in a number equal to the total number of pieces of Scheduling Grant including the UL Scheduling Grant S_(USCB) and DL Scheduling Grant S_(DSCB) as PDCCH's (Physical Downlink Control Channels) S_(DCCB), and outputs them (Step S7). The PDCCH's (Physical Downlink Control Channels) S_(DCCD) with which the UL Scheduling Grant S_(USCB) is multiplexed are generated in a number equal to the number of frequency blocks.

The downlink RS signal generator 112 generates a downlink RS signal as a downlink RS signal S_(DRSB); the downlink data signal generator 113 receives the DL Scheduling Grant S_(DSCB) as input, multiplexes downlink data signals from a plurality of mobile stations together in accordance with an RB pattern indicated by the DL Scheduling Grant S_(DSCB), generates Physical Downlink Shared Channel (PDSCH) S_(DDCB), and outputs it (Step S8).

The multiplexer 114 receives the PDCCH S_(DCCB), RS signal S_(DRSB) and PDSCH S_(DDCB) as input, and multiplexes these signals to generate a multiplexed downlink signal S_(MUXB); the transmitter 115 generates a transmit signal S_(TXB) from the multiplexed downlink signal S_(MUXB), and transmits it (Step S9).

The receiver 201 in the mobile station 200 receives a signal from the base station 100, establishes downlink synchronization using a guard interval, and outputs a mobile station receive signal S_(RXU) (Step S10).

The downlink RS (Reference Signal) separator 202 receives the mobile station receive signal S_(RXU) as input, separates therefrom a downlink RS signal S_(DRSU) in which the downlink RS signals are multiplexed, and outputs it; the downlink CQI measurement section 203 calculates CQI on an RB-by-RB basis from the downlink RS signal S_(DRSU), and outputs it as downlink CQI information S_(DCQB) (Step S11).

The downlink control signal separator 206 receives the mobile station receive signal S_(RXU) as input, separates therefrom PDCCH S_(DCCU) in which downlink control signals from a plurality of mobile stations are multiplexed, and outputs it (Step S12).

The downlink control signal demodulator 207 demodulates the PDCCH S_(DCCU) to reproduce a downlink control signal, separates therefrom a result of reproduction in which mobile station identification information corresponding to the mobile station itself is multiplexed, and outputs it as a reproduced downlink control signal S_(DCMU) (Step S13).

The downlink scheduling information extracting section 208 receives the reproduced downlink control signal S_(DCMU) as input, extracts therefrom downlink RB allocation decision information S_(DSCU) corresponding to downlink resource allocation information, and outputs it (Step S14).

The uplink scheduling information extracting section 210 extracts, from the reproduced downlink control signal S_(DCMU), each piece of UL Scheduling Grant, which represents information on allocated uplink RBs, identifies RBs indicated by the uplink RB allocation information, and outputs it as uplink RB allocation decision information S_(USCU) (Step S15).

The uplink control signal generator 211 receives the uplink RB allocation decision information S_(USCU) and downlink CQI information S_(DCQB) as input, generates Physical Uplink Control Channel (PUCCH) S_(UCCU) in which the downlink CQI information S_(DCQB) is multiplexed with a predetermined resource for a control signal indicated by the uplink RB allocation decision information S_(USCU), and outputs it (Step S16).

The uplink RS signal generator 212 receives the uplink RB allocation decision information S_(USCU) as input, generates an uplink RS transmit signal S_(URSU) using a resource for RS predetermined in the uplink RB allocation decision information S_(USCU), and outputs it (Step S17).

The uplink data signal generator 213 receives the uplink RB allocation decision information S_(USCU) as input, generates Physical Uplink Shared Channel (PUSCH) S_(UDCU) using a resource for a data signal predetermined in the uplink RB allocation decision information S_(USCU), and outputs it (Step S18).

The multiplexer 214 receives the PUCCH S_(UCCU), uplink RS transmit signal S_(URSU), PUSCH S_(UDCU) and downlink control signal decision signal S_(DAKU) as input, and multiplexes these signals to generate a multiplexed mobile station signal S_(MUXU); the transmitter 215 transmits the multiplexed mobile station signal S_(MUXU) to the base station 100 (Step S19).

While in accordance with the above-described embodiment, the description has been made with reference to a case in which information on resource allocation is represented in the Tree Based method, any method other than the Tree Based method may be employed.

Moreover, while a mode in which the number of frequency blocks is determined from a condition of mobile station's channel quality (CQI measured by a sounding reference signal) is described in this embodiment, it may be contemplated that this embodiment uses information about a communication environment, such as, for example, the cell size, system bandwidth, coverage of a base station, bandwidth of an uplink sounding reference signal, bandwidth used in uplink data transmission, number of levels in multi-level modulation and code rate used in uplink data transmission, transmittable/receivable bandwidth of a mobile station (sometimes referred to as UE capability), and type of uplink transmission data (VoIP, HTTP, FTP etc.), or information affecting the communication environment, such as the billing scheme in which a user signs on, power headroom (which is a difference between the maximum transmit power of a mobile station and an actual transmit power of the mobile station), and target SINR in uplink power control. Further, since the above-described cell size is determined by information affecting the communication environment, such as the location of a base station, distance between base stations, and interference power, these information may be used to select a number of frequency blocks.

Furthermore, while a mode in which the number of frequency blocks determined in accordance with uplink CQI is equal to the number of PDCCH's has been described in the above-described embodiment, a mode in which the maximum number of frequency blocks determined in accordance with uplink CQI is equal to the number of PDCCH's may be contemplated. In this case, as shown in FIG. 5, the base station is provided with a maximum-number-of-frequency-blocks determining section 105 for determining a maximum number of frequency blocks determined in accordance with uplink CQI. On the other hand, the mobile station is provided with a maximum-number-of-frequency-blocks extracting section 209, as shown in FIG. 6. It should be noted that the maximum number of frequency blocks refers to a maximum number of frequency blocks that can be allocated to one terminal.

Now another method of determining a maximum number of frequency blocks will be described hereinbelow.

First, a configuration will be described in which the maximum-number-of-frequency-blocks determining section determines the maximum number of frequency blocks in accordance with the location of the mobile station and the base station.

FIG. 7 shows a block diagram of a base station 100 for determining the maximum number of frequency blocks in accordance with the location of the mobile station and the base station.

In the base station 100, the uplink control signal demodulator 109 demodulates PUCCH S_(UCCB), and outputs a downlink CQI measurement signal S_(DCQB), which is a result of measurement of downlink CQI transmitted by a plurality of mobile stations, and received mobile station localization information S_(ULCB), which represents the location of the mobile station.

A maximum-number-of-frequency-blocks determining section 105-1 receives the received mobile station localization information S_(ULCB) as input, determines a maximum number of frequency blocks in frequency resources to be allocated to each mobile station from the location of the mobile station represented by the received mobile station localization information S_(ULCB), generates a maximum-frequency-block signal S_(UDFB) for each mobile station, and outputs it. In particular, the maximum number of frequency blocks is determined and generated to have a smaller value for a user located farther away from the base station.

FIG. 8 shows a block diagram of a mobile station 200 when a maximum number of frequency blocks is determined in accordance with the location of the mobile station and the base station.

In the mobile station 200, a localizing section 416 has a function of locating the mobile station using a signal from a GPS signal satellite, and it receives a signal from the GPS satellite, locates the mobile station 200, generates mobile station localization information S_(ULCU), and outputs it.

An uplink control signal generator 211-1 receives the uplink RB allocation decision information S_(USCU), downlink CQI information S_(DCQB), and mobile station localization information S_(ULCU) as input, generates PUCCH S_(UCCU) using a predetermined resource for a control signal in resources indicated by the uplink RB allocation decision information S_(USCU) along with the downlink CQI information S_(DCQB) and mobile station localization information S_(ULCU), and outputs it.

By the aforementioned configuration, RBs are allocated with a lower allocation resolution to a mobile station having a smaller maximum number of frequency blocks, and with a higher allocation resolution to a mobile station having a larger maximum number of frequency blocks.

Subsequently, a case will be described in which the maximum-number-of-frequency-blocks determining section determines a maximum number of frequency blocks in accordance with the power headroom, which represents an increasable transmit power in a mobile station.

FIG. 9 shows a block diagram of a base station 100 in which the maximum number of frequency blocks is determined in accordance with the power headroom, which represents an increasable transmit power in a mobile station.

In the base station 100, an uplink transmit power determining section 517 receives the uplink CQI information S_(UCQB) as input, calculates a transmit power value for the mobile station required to satisfy a required receive power, generates uplink transmit power setting information S_(UPWB), and outputs it.

The uplink control signal demodulator 109 demodulates the uplink control signal S_(UCCB), and outputs a downlink CQI measurement signal S_(DCQB), which is a result of measurement of downlink CQI transmitted by a plurality of mobile stations, and mobile station's received power headroom information S_(UHRB).

A maximum-number-of-frequency-blocks determining section 105-2 receives the received power headroom information S_(UHRB) as input, determines a maximum number of frequency blocks in frequency resources to be allocated to each mobile station based on the received power headroom information S_(UHRB), generates a maximum-frequency-block signal S_(UDFB) for the mobile station, and outputs it. In particular, for example, setting the initial value of the maximum number of frequency blocks as one, and in a case that the value represented by the received power headroom information S_(UHRB) exceeds a threshold electric power P_(DFUP) (P_(DFUP) is a positive real number), the value of the maximum number of frequency blocks is incremented by one. In a case that the value represented by the received power headroom information S_(UHRB) is zero and the maximum number of frequency blocks is two or more, the value of the maximum number of frequency blocks is decremented by one. That is, in a case that the transmit power has an extra capacity, the maximum number of frequency blocks is increased to increase the number of allocatable frequency blocks, and enhance the gain in frequency domain channel dependent scheduling. In a case that the transmit power has no extra capacity and is power-limited, the maximum number of frequency blocks is reduced to transmit signals with higher electric power density.

The downlink control signal generator 511 receives the mobile station identification information S_(UIDB), UL Scheduling Grant S_(USCB), DL Scheduling Grant S_(DSCB), maximum-frequency-block signal S_(UDFB) and uplink transmit power setting information S_(UPWB) as input, generates a downlink control signal in which these signals are multiplexed as PDCCH S_(DCCB), and outputs it.

FIG. 10 shows a block diagram of a mobile station 200 in which the maximum number of frequency blocks is determined in accordance with the power headroom, which represents an increasable transmit power in the mobile station.

In the mobile station 200, an uplink transmit power information extracting section 616 extracts, from the reproduced downlink control signal S_(DCMU), received uplink transmit power setting value information S_(USCU) that represents the uplink transmit power value in the mobile station and is notified by the base station, and outputs it.

A power headroom calculating section 617 receives the received uplink transmit power setting value information S_(USCDU) as input, subtracts the received uplink transmit power setting value information S_(USCU) from the maximum transmit power value transmittable by the mobile station, and outputs the resulting value as mobile station power headroom information S_(UHRU). The mobile station power headroom information S_(UHRU) represents the remaining electric power with which the mobile station can perform additional transmission after transmission with an electric power represented by the received uplink transmit power setting value information S_(USCU).

An uplink control signal generator 211-2 receives the uplink RB allocation decision information S_(USCU), downlink CQI information S_(DCQB), and mobile station power headroom information S_(UHRU) as input, generates PUCCH S_(UCCU) using a predetermined resource for a control signal in resources indicated by the uplink RB allocation decision information S_(USCU) along with the downlink CQI information S_(DCQB) and mobile station power headroom information S_(UHRU), and outputs it.

It should be noted that the maximum frequency blocks may be, in addition to the positional relationship between a mobile station and a base station or power headroom, information about a communication environment such as the condition of mobile station's channel quality, a cell size, a system bandwidth, coverage of a base station, a bandwidth of an uplink sounding reference signal, a bandwidth used in uplink data transmission, the number of levels in multi-level modulation and a code rate used in uplink data transmission, a transmittable/receivable bandwidth of a mobile station (sometimes referred to as UE capability), and a type of uplink transmission data (VoIP, HTTP, FTP etc.), or information affecting the communication environment, such as the billing scheme in which a user signs on, and a target SINR in uplink power control.

As described above, by generating a number of PDCCH's, which number is equal to the number of frequency blocks, with resource block allocation information of a required minimum number of bits, useless resources in PDCCH can be reduced.

Second Embodiment

The foregoing embodiment has addressed a mode in which Uplink Scheduling Grant and control signals PDCCH's for notifying the Uplink Scheduling Grant to a terminal are generated in a number equal to the number of frequency blocks or the maximum number of frequency blocks. In the following embodiment, a mode in which a base station notifies the number of frequency blocks to a mobile station in the foregoing embodiment will be described. It should be noted that components similar to those in the foregoing embodiment are designated by similar reference numerals and detailed description thereof will be omitted.

The uplink scheduler 104 outputs resource allocation information representing positions of allocated RBs as UL Scheduling Grant S_(USCB), and a determined number of frequency blocks as S_(UDFB).

The downlink control signal generator 111 is supplied with the UL Scheduling Grant S_(USCB), mobile station identification signal S_(UIDB), and DL Scheduling Grant S_(DSCB) as input, multiplexes the mobile station identification signal S_(UIDB) with each of the plurality of pieces of UL Scheduling Grant and DL Scheduling Grant, and generates a downlink control signal PDCCH S_(DCCB) from each of the plurality of pieces of UL Scheduling Grant, and moreover, generates a downlink control signal PDCCH S_(DCCB) from the DL Scheduling Grant. The downlink control signals PDCCH's S_(DCCB) are generated as the downlink control signal PDCCH S_(DCCB) for UL Scheduling Grant S_(USCB) and that for the DL Scheduling Grant S_(DSCB). In other words, the downlink control signals PDCCH's S_(DCCB) are generated in a number equal to the total number of pieces of Scheduling Grant including the UL Scheduling Grant S_(USCB) and DL Scheduling Grant S_(DSCB). The downlink control signal PDCCH S_(DCCB) is multiplexed with information bits indicating a DCI (Downlink Control Information) format, which is an identifier for distinguishing between the UL Scheduling Grant and DL Scheduling Grant. For example, a DCI format of zero is multiplexed for UL Scheduling Grant and of one for DL Scheduling Grant in the downlink control signal PDCCH S_(DCCB). Furthermore, the number of frequency blocks S_(UDFB) is received as input to generate a higher-layer control signal, which is output in PBCH (Physical Broadcast Channel).

The downlink control signal separator 206 receives the mobile station receive signal S_(RXU) as input, separates therefrom PDCCH S_(DCCU) in which downlink control signals from a plurality of mobile stations are multiplexed and PBCH, and outputs them.

The downlink control signal demodulator 207 receives the PBCH as input, demodulates it to reproduce a higher-layer control signal, and separates therefrom a result of reproduction in which mobile station identification information corresponding to the mobile station itself is multiplexed. Then, it recognizes the number of PDCCH's destined to the mobile station itself from the number of frequency blocks in the reproduced higher-layer control signal, and when the number of demodulated PDCCH's destined to the mobile station itself reaches a number equal to the number of frequency blocks, terminates demodulation of PDCCH.

Subsequently, an operation of this embodiment will be described with reference to a flow chart in FIG. 11.

The receiver 101 in the base station 100 receives a signal from the mobile station 200, establishes uplink synchronization using a guard interval, and outputs a base station receive signal S_(RXB) (Step S1).

The uplink RS (Reference Signal) separator 102 separates from the output base station receive signal S_(RXB) an uplink RS signal S_(URSB) in which uplink RS signals from a plurality of mobile stations are multiplexed, and outputs it (Step S2).

From the uplink RS signals S_(URSB) for a plurality of mobile stations, the uplink CQI measurement section 103 calculates CQI (Channel Quality Indicator) for each mobile station on an RB-by-RB basis, and outputs it as uplink CQI information S_(UCQB) (Step S3).

The uplink scheduler 104 determines a number of frequency blocks for resources to be allocated to each mobile station based on the uplink CQI information S_(UCQB) for each mobile station (Step S4).

RBs are allocated so that the determined number of frequency blocks is attained (Step S5).

Next, the uplink scheduler 104 generates information representing positions of the allocated RBs for each frequency block, and outputs it as a number of pieces of UL Scheduling Grant S_(USCB) each having 13 bits, which number is equal to the number of frequency blocks. Moreover, the determined frequency blocks is output as S_(UDFB) (Step S6).

The downlink control signal generator 111 is supplied with the UL Scheduling Grant S_(USCB), DL Scheduling Grant S_(DSCB) and mobile station identification information S_(UIDB) as input, multiplexes the mobile station identification information S_(UIDB) with each of the plurality of pieces of UL Scheduling Grant S_(USCB) and DL Scheduling Grant S_(DSCB), generates downlink control signals in a number equal to the total number of pieces of Scheduling Grant including the UL Scheduling Grant S_(USCB) and DL Scheduling Grant S_(DSCB) as PDCCH's (Physical Downlink Control Channels) S_(DCCB), and outputs them. The PDCCH's (Physical Downlink Control Channels) S_(DCCB) with which the UL Scheduling Grant S_(USCB) is multiplexed are generated in a number equal to the number of frequency blocks. Moreover, it receives the number of frequency blocks S_(UDFB) as input, and generates a higher-layer control signal, which is output in PBCH (Step S7).

The downlink RS signal generator 112 generates a downlink RS signal as a downlink RS signal S_(DRSB); the downlink data signal generator 113 multiplexes downlink data signals from a plurality of mobile stations together in accordance with an RB pattern indicated by the DL Scheduling Grant S_(DSCB), generates Physical Downlink Shared Channel (PDSCH) S_(DDCB), and outputs it (Step S8).

The multiplexer 114 receives the PDCCH S_(DCCB), RS signal S_(DRSB) and PDSCH S_(DDCB) as input, and multiplexes these signals to generate a multiplexed downlink signal S_(MUXB); the transmitter 115 generates a transmit signal S_(TXB) from the multiplexed downlink signal S_(MUXB), and transmits it (Step S9).

The receiver 201 in the mobile station 200 receives a signal from the base station 100, establishes downlink synchronization using a guard interval, and outputs a mobile station receive signal S_(RXU) (Step S10).

The downlink RS (Reference Signal) separator 202 receives the mobile station receive signal S_(RXU) as input, and separates therefrom a downlink RS signal S_(DRSU) in which the downlink RS signals are multiplexed; the downlink CQI measurement section 203 calculates CQI on an RB-by-RB basis from the downlink RS signal S_(DRSU), and outputs it as downlink CQI information S_(DCQB) (Step S11).

The downlink control signal separator 206 receives the mobile station receive signal S_(RXU) as input, separates therefrom PDCCH S_(DCCU) in which downlink control signals from a plurality of mobile stations are multiplexed and PBCH, and outputs them (Step S12).

The downlink control signal demodulator 207 receives the PBCH as input, demodulates it to reproduce a higher-layer control signal, separates therefrom a result of reproduction in which mobile station identification information corresponding to the mobile station itself is multiplexed, recognizes the number of PDCCH's destined to the mobile station itself from the number of frequency blocks in the reproduced higher-layer control signal, and when the number of demodulated PDCCH's destined to the mobile station itself reaches a number equal to the number of frequency blocks, terminates demodulation of PDCCH (Step S20).

The downlink control signal demodulator 207 receives the PDCCH S_(DCCU) as input, demodulates it to reproduce a downlink control signal, separates therefrom a result of reproduction in which mobile station identification information corresponding to the mobile station itself is multiplexed, and outputs it as a reproduced downlink control signal S_(DCMU) (Step S13).

The downlink scheduling information extracting section 208 receives the reproduced downlink control signal S_(DCMU) as input, extracts therefrom downlink RB allocation decision information S_(DSCU) corresponding to downlink resource allocation information, and outputs it (Step S14).

The uplink scheduling information extracting section 210 extracts, from the reproduced downlink control signal S_(DCMU), UL Scheduling Grant, which represents information on allocated uplink RBs, identifies RBs indicated by the uplink RB allocation information, and outputs it as uplink RB allocation decision information S_(USCU) (Step S15).

The uplink control signal generator 211 receives the uplink RB allocation decision information S_(USCU) and downlink CQI information S_(DCQB) as input, generates Physical Uplink Control Channel (PUCCH) S_(USCU) in which the downlink CQI information S_(DCQB) is multiplexed with a predetermined resource for a control signal indicated by the uplink RB allocation decision information S_(USCU), and outputs it (Step S16).

The uplink RS signal generator 212 receives the uplink RB allocation decision information S_(USCU) as input, generates an uplink RS transmit signal S_(URSU) using a resource for RS predetermined in the uplink RB allocation decision information S_(USCU), and outputs it (Step S17).

The uplink data signal generator 213 receives the uplink RB allocation decision information S_(USCU) as input, generates Physical Uplink Shared Channel (PUSCH) S_(UDCU) using a resource for a data signal predetermined in the uplink RB allocation decision information S_(USCU), and outputs it (Step S18).

The multiplexer 214 receives the PUCCH S_(UCCU), uplink RS transmit signal S_(URSU), PUSCH S_(UDCU) and downlink control signal decision signal S_(DAKU) as input, and multiplexes these signals to generate a multiplexed mobile station signal S_(MUXU); the transmitter 215 transmits the multiplexed mobile station signal S_(MUXU) to the base station 100 (Step S19).

While the number of frequency blocks is described above as being notified through PBCH, it is additionally notified with a higher-layer control signal mapped to PDSCH (Physical Downlink Shared Channel) or the like. Moreover, in a case that the maximum frequency block is determined on a mobile station-by-mobile station basis, a base station may be configured to notify the maximum frequency block to a mobile station.

As described above, by notifying beforehand, from a base station to a mobile station, the number of frequency blocks corresponding to the number of PDCCH's transmitted to a mobile station or the maximum number of frequency blocks, the present invention may provide an additional effect of reducing the processing load on the mobile station. For example, according to LTE, a mobile station obtains PDCCH destined to the mobile station itself by checking information on a mobile station identifier multiplexed with PDCCH as to whether it is destined to the mobile station itself When the number of demodulated PDCCH's destined to the mobile station itself reaches the number of frequency blocks or the maximum number of frequency blocks notified by base station, the mobile station can terminate PDCCH demodulation processing. In other words, the mobile station does not need to demodulate all PDCCH's, so that its processing load can be reduced.

Third Embodiment

The following embodiment will address a mode in which the number of bits for UL Scheduling Grant can be reduced. It should be noted that components similar to those in the foregoing embodiments are designated by similar reference numerals and detailed description thereof will be omitted. While the following description will be made with reference to the second embodiment, it may be based on the first embodiment.

An uplink scheduler 104 makes uplink scheduling for each mobile station. The uplink scheduler 104 determines a number of frequency blocks for resources to be allocated based on the uplink CQI information S_(UCQB). RBs are allocated with an allocation resolution determined in accordance with the determined number of frequency blocks and with the determined number of frequency blocks. Once the allocation resolution has been determined, a structure in the Tree-Based method representing positions of the allocated RBs is determined accordingly. Scheduling information of the resource allocation information for each frequency block representing the positions of the allocated RBs in a Tree-Based form and the value of the allocation resolution is generated for each frequency block, that is, UL Scheduling Grant S_(USCB) for a number of frequency blocks is output in a number of bits in accordance with the determined structure in the Tree-Based method. The number of frequency blocks is also output as S_(UDFB). While the value of the allocation resolution may be written in all pieces of UL Scheduling Grant, it may be written in a first notified piece of UL Scheduling Grant.

Now processing in the uplink scheduler 104 will be specifically described next.

The uplink scheduler 104 modifies and sets a minimal frequency bandwidth in resource allocation, that is, an allocation resolution, which is a minimal unit for resource block allocation, in accordance with the number of frequency blocks determined based on the uplink CQI information S_(UCQB). Specifically, a higher allocation resolution is set for a larger number of frequency blocks.

Next, a specific example will be described below, in which the number of signaling bits for use in resource allocation for one user is held down within 14 bits for a system band having 10 RBs.

Resource allocation at the uplink scheduler 104 is made using a correspondence table representing a relationship between the number of frequency blocks and allocation resolution, as shown in FIG. 12. The correspondence table is defined depending upon a communication environment, etc. For example, a higher allocation resolution is defined for a larger number of frequency blocks. By using this relationship, it is possible to hold the number of signaling bits down to 14 bits including notification of the value of the allocation resolution (2 bits) for a number of frequency blocks of four or smaller.

Assume that there are four mobile stations UE1, UE2, UE3, UE4, and the number of frequency blocks allocated to UE1 is three, that allocated to UE2 is two, that allocated to UE3 is one, and that allocated to UE4 is one. Now representing the resource blocks shown in FIG. 13 as RB0, RB1, . . . , RB8, RB9 in sequence from left to right, it is assumed that scheduling is made to allocate RB0, RB1, RB4, RB5, RB8 and RB9 to UE1, RB3 and RB6 to UE2, RB2 to UE3, and RB7 to UE4. Now a case in which the scheduling in FIG. 13 and relationship between the number of frequency blocks and allocation resolution in FIG. 12 are used will be described. FIGS. 14, 15, 16 and 17 show examples of RB allocation and UL Scheduling Grant using the Tree-Based method for UE1, UE2, UE3 and UE4, respectively.

Since the number of frequency blocks is one for UE3 and UE4, the allocation resolution is 1 RB with reference to the correspondence table in FIG. 12. Therefore, when allocating resource blocks to UE3 and UE4, they are allocated such that one resource block is allocated with a number of frequency blocks within one. To represent a resource corresponding to one frequency block within the whole band, 10 RBs, in the Tree-Based method with an allocation resolution of 1 RB, a value of any one of 1-55 is required (6 bits). Referring to FIGS. 16 and 17, values of 1-55 representing resources of one frequency block are arranged in a tree structure. The tree structure in the Tree-Based method varies with the allocation resolution. In other words, the number of bits for UL Scheduling Grant also varies.

For example, referring to FIG. 18, when the allocation resolution is 1 RB, the tree structure is constructed from a number sequence of 1-55 that can be expressed by 6 bits. When the allocation resolution is 2 RBs, allocation is made for each unit of two resource blocks, so that it can be handled with a number sequence similar to that for a system band of 5 RBs. Accordingly, the tree structure is constructed from a number sequence of 1-15. By correlating the tree structure with the determined number of frequency blocks in a one-to-one correspondence, and notifying the allocation resolution or number of frequency blocks to the mobile station, a tree structure in the Tree-Based method can be discriminated.

Since scheduling is made with a number of frequency blocks=1 for UE3 and UE4, one piece of UL Scheduling Grant is generated for UE3 and UE4. The number of bits in the UL Scheduling Grant is 6+2 bits=8 bits, including notification of the value of the allocation resolution. Fields represented by the UL Scheduling Grant to be notified to UE3 include a value of the allocation resolution of “1” and a position of “2” (“2” in FIG. 16), which is the position of an allocated resource block represented in a tree structure. UL Scheduling Grant for UE4 has 8 bits, and a value of the allocation resolution of “1” and a position represented in a tree structure, “7” (“7” in FIG. 17), are notified thereto.

For UE2, the number of frequency blocks is two, and therefore, the allocation resolution is 1 RB with reference to the correspondence table in FIG. 12. To represent a resource corresponding to one frequency block within the whole band, 10 RBs, in the Tree-Based method with an allocation resolution of 1 RB, a value of any one of 1-55 that can be denoted by 6 bits is used. Since scheduling is made with two frequency blocks for UE2, two pieces of UL Scheduling Grant are generated for UE2. The number of bits in the UL Scheduling Grant includes UL Scheduling Grant of 6+2 bits=8 bits and UL Scheduling Grant of 6 bits, including notification of the value of the allocation resolution. Fields represented by the UL Scheduling Grant to be notified to UE2 include a value of the allocation resolution of “1” and positions of allocated resource blocks represented in a tree structure, “3” and “6” (“3” and “6” in FIG. 15). It should be noted that in a case of the value of the allocation resolution is written in all pieces of UL Scheduling Grant, two pieces of UL Scheduling Grant of 6+2 bits=8 bits are used.

For UE1, the number of frequency blocks is three, and therefore, the allocation resolution is 2 RBs with reference to the correspondence table in FIG. 12. To represent a resource corresponding to one frequency block within the whole band, 10 RBs, in the Tree-Based method with an allocation resolution of 2 RBs, a value of any one of 1-15, which can be denoted by 4 bits, is used. Since scheduling is made with three frequency blocks for UE1, three pieces of UL Scheduling Grant are generated for UE1. The number of bits in the UL Scheduling Grant includes UL Scheduling Grant of 4+2 bits=6 bits and two pieces of UL Scheduling Grant of 4 bits, including notification of the value of the allocation resolution. Fields represented by the UL Scheduling Grant to be notified to UE1 include a value of the allocation resolution of “2” and positions of allocated resource blocks represented in a tree structure, “0”, “2” and “4” (“0”, “2” and “4” in FIG. 14). It should be noted that in a case of the value of the allocation resolution is written in all pieces of UL Scheduling Grant, three pieces of UL Scheduling Grant of 4+2 bits=6 bits are used. By thus increasing the allocation resolution, the amount of information on resource allocation can be held down even for an increased number of frequency blocks.

Next, a general method of generating resource allocation information in a tree structure will be described. An example of an allocation resolution of P resource blocks (P is one or more) and a number of frequency blocks of n (n is one or more) will be described hereinbelow with reference to EQ. 1. In this example, one frequency block is defined as P (allocation resolution) consecutive resource blocks. Resource allocation information is composed of n resource indicator values (RIV's). The resource indicator value RIV_(n) for an n-th frequency block represents a frequency block at start (RBG_(start,n)) and a length of subsequent frequency blocks (L_(CRBGs,n)). The n-th resource indicator value RIV_(n) is defined by EQ. 1 below:

if

(L _(CRBGs,n)−1)≦└N _(RBG) ^(UL)/2┘

then

RIV_(n) =N _(RB) ^(UL)(L _(CRBGs,n)−1)+RBG _(START,n)

else

RIV_(n) =N _(RBG) ^(UL)(N _(RBG) ^(UL) −L _(CRBGs,n)+1)+(N _(RBG) ^(UL)−1−RBG _(START,n))   (EQ. 1)

where N^(UL) _(RBG) is the number of frequency blocks in the whole system.

The number of resource blocks in the whole system is N^(UL) _(RBG)×P (allocation resolution).

While the following description will be made with reference to a configuration in which UL Scheduling Grant is generated in a number equal to the number of frequency blocks as described above, other configurations may be employed. For example, a configuration in which information on allocation of a plurality of frequency blocks is written in one piece of UL Scheduling Grant to reduce the number of pieces of UL Scheduling Grant relative to the number of frequency blocks may be contemplated. Here, such a configuration will be described below with reference to a case in which UE1 has a number of frequency blocks of three and two pieces of UL Scheduling Grant are generated.

One piece of UL Scheduling Grant has information on a resource corresponding to one frequency block and the value of the allocation resolution (4+2 bits=6 bits) incorporated therein, and the other piece of UL Scheduling Grant has information on a resource corresponding to two frequency blocks (4+4 bits=8 bits) incorporated therein. Alternatively, one piece of UL Scheduling Grant may have information on a resource corresponding to two frequency blocks and the value of the allocation resolution (4+4+2 bits=10 bits) incorporated therein, and the other piece of UL Scheduling Grant may have information on a resource (4 bits) corresponding to one frequency block incorporated therein. In a case that the maximum number of bits that can be incorporated in UL Scheduling Grant is determined beforehand, the number of pieces of information on allocation of frequency blocks to be incorporated one piece of UL Scheduling Grant may be determined depending upon the number of bits.

While in accordance with the second embodiment, a base station notifies the number of frequency blocks to a mobile station, the number of frequency blocks is different from the number of PDCCH's (Physical Downlink Control Channels) in a case that the number of pieces of UL Scheduling Grant is smaller than the number of frequency blocks in this embodiment, so that the base station notifies the number of PDCCH's (Physical Downlink Control Channels) to the mobile station. As a result, the number of demodulation operations on PDCCH (Physical Downlink Control Channel) in a terminal may be further reduced relative to that in the second embodiment. The thus-generated UL Scheduling Grant S_(USCB) is input to the downlink control signal generator 111. The downlink control signal generator 111 is also supplied as input with the DL Scheduling Grant S_(DSCB), mobile station identification information S_(UIDB), and frequency-block signal S_(UIDB). It multiplexes the mobile station identification signal S_(UIDB) with each of the plurality of pieces of UL Scheduling Grant and DL Scheduling Grant, generates a downlink control signal PDCCH S_(DCCB) from each of the plurality of pieces of UL Scheduling Grant, and moreover, generates a downlink control signal PDCCH S_(DCCB) from the DL Scheduling Grant. The downlink control signal's PDCCH's S_(DCCB) are generated in a number equal to the total number of pieces of Scheduling Grant including the UL Scheduling Grant S_(USCB) and DL Scheduling Grant S_(USCB). Moreover, the downlink control signal PDCCH S_(DCCB) is multiplexed with information bits indicating a DCI (Downlink Control Information) format, which is an identifier for distinguishing between the UL Scheduling Grant and DL Scheduling Grant. For example, a DCI format of zero is multiplexed for UL Scheduling Grant and of one for DL Scheduling Grant in the downlink control signal PDCCH S_(DCCB).

The downlink control signal demodulator 207 receives the PDCCH S_(DCCU) as input, demodulates it to reproduce a downlink control signal, separates therefrom a result of reproduction in which the mobile station identification information corresponding to the mobile station itself is multiplexed, and outputs it as a reproduced downlink control signal S_(DCMU). It should be noted that the PDCCH's for the mobile station itself are multiplexed in a number equal to the number of frequency blocks allocated to the mobile station itself

The uplink scheduling information extracting section 210 extracts, from the reproduced downlink control signal S_(DCMU), UL Scheduling Grant that represents information on allocated uplink RBs. Next, it discriminates a tree structure in the Tree-Based method from the value of the allocation resolution contained in the UL Scheduling Grant, identifies an RB indicated by the uplink RB allocation information in this tree structure, and outputs it as uplink RB allocation decision information S_(USCU).

Subsequently, an operation of this embodiment will be described with reference to a flow chart in FIG. 19.

The receiver 101 in the base station 100 receives a signal from the mobile station 200, establishes uplink synchronization using a guard interval, and outputs a base station receive signal S_(RXB) (Step S1).

The uplink RS (Reference Signal) separator 102 separates from the output base station receive signal S_(RXB) an uplink RS signal S_(URSB) in which uplink RS signals from a plurality of mobile stations are multiplexed, and outputs it (Step S2).

From the uplink RS signals S_(URSB) for a plurality of mobile stations, the uplink CQI measurement section 103 calculates CQI (Channel Quality Indicator) for each mobile station on an RB-by-RB basis, and outputs it as uplink CQI information S_(UCQB) (Step S3).

The uplink scheduler 104 determines a number of frequency blocks for resources to be allocated to each mobile station based on the uplink CQI information S_(UCQB) for each mobile station (Step S4).

An allocation resolution correlated with the determined number of frequency blocks is determined using the correspondence table as shown in FIG. 12 kept in the equipment itself, whereby a structure in the Tree-Based method is determined, and the number of bits for UL Scheduling Grant is set as a number of bits in accordance with the determined structure in the Tree-Based method (Step S21).

RBs are allocated with resource blocks in a number equal to the determined allocation resolution and with the determined number of frequency blocks (Step S5-1).

Next, the uplink scheduler 104 outputs information representing positions of the allocated RBs in a Tree-Based form and the value of the allocation resolution in a specified number of bits as UL Scheduling Grant S_(USCB) for each frequency block, and outputs the number of frequency blocks as S_(UDFB) (Step S6).

The downlink control signal generator 111 is supplied with the UL Scheduling Grant S_(USCB), DL Scheduling Grant S_(DSCB), mobile station identification information S_(UIDB), and frequency-block signal S_(UDFB) as input, multiplexes mobile station identification information S_(UIDB) with each of the plurality of pieces of UL Scheduling Grant S_(USCB) and DL Scheduling Grant S_(DSCB), generates downlink control signals in a number equal to the total number of pieces of Scheduling Grant including the UL Scheduling Grant S_(USCB) and DL Scheduling Grant S_(DCCB) as PDCCH's (Physical Downlink Control Channels) S_(DCCB), and outputs them. The PDCCH's (Physical Downlink Control Channels) S_(DCCB) with which the UL Scheduling Grant S_(USCB) is multiplexed are generated in a number equal to the number of frequency blocks. Moreover, it uses the number of frequency blocks S_(UDFB) as input to generate a higher-layer control signal, which is output in PBCH (Step S7).

The downlink RS signal generator 112 generates a downlink RS signal as a downlink RS signal S_(DRSB), and outputs it; the downlink data signal generator 113 receives the DL Scheduling Grant S_(DSCB) as input, multiplexes downlink data signals from a plurality of mobile stations together in accordance with an RB pattern indicated by the DL Scheduling Grant S_(DSCB), generates Physical Downlink Shared Channel (PDSCH) S_(DDCB), and outputs it (Step S8).

The multiplexer 114 receives the PDCCH S_(DCCB), RS signal S_(DRSB) and PDSCH S_(DDCB) as input, multiplexes these signals to generate a multiplexed downlink signal S_(MUXB), and outputs it; the transmitter 115 receives the multiplexed downlink signal S_(MUXB) as input, generates a transmit signal S_(TXB), and outputs it (Step S9).

The receiver 201 in the mobile station 200 receives a signal from the base station 100, establishes downlink synchronization using a guard interval, and outputs a mobile station receive signal S_(RXU) (Step S10).

The downlink RS (Reference Signal) separator 202 receives the mobile station receive signal S_(RXU) as input, and separates therefrom a downlink RS signal S_(DRSU) in which the downlink RS signals are multiplexed; the downlink CQI measurement section 203 receives the downlink RS signal S_(DRSU) as input, calculates CQI on an RB-by-RB basis, and outputs it as downlink CQI information S_(DCQB) (Step S11).

The downlink control signal separator 206 receives the mobile station receive signal S_(RXU) as input, and separates therefrom PDCCH S_(DCCU) in which downlink control signals from a plurality of mobile stations are multiplexed; the downlink control signal demodulator 207 demodulates the PDCCH S_(DCCU) to reproduce a downlink control signal, separates therefrom a result of reproduction in which mobile station identification information corresponding to the mobile station itself is multiplexed, and outputs it as a reproduced downlink control signal S_(DCMU) (Step S12).

The downlink control signal demodulator 207 receives the PBCH as input, demodulates it to reproduce a higher-layer control signal, separates therefrom a result of reproduction in which mobile station identification information corresponding to the mobile station itself is multiplexed, recognizes the number of PDCCH's destined to the mobile station itself from the number of frequency blocks in the reproduced higher-layer control signal, and when the number of demodulated PDCCH's destined to the mobile station itself reaches a number equal to the number of frequency blocks, terminates demodulation of PDCCH (Step S20).

The downlink scheduling information extracting section 208 receives the reproduced downlink control signal S_(DCMU) as input, extracts therefrom downlink RB allocation decision information S_(DSCU) corresponding to downlink resource allocation information, and outputs it (Step S13).

The uplink scheduling information extracting section 210 extracts, from the reproduced downlink control signal S_(DCMU), UL Scheduling Grant, which represents information on allocated uplink RBs, and checks the value of the allocation resolution (Step S22).

Next, it discriminates a tree structure in the Tree-Based method from the value of the allocation resolution, identifies RBs indicated by the uplink RB allocation information in this tree structure, and outputs it as uplink RB allocation decision information S_(USCU) (Step S14-1).

The uplink control signal generator 211 receives the uplink RB allocation decision information S_(USCU) and downlink CQI information S_(DCQB) as input, generates Physical Uplink Control Channel (PUCCH) S_(UCCU) in which the downlink CQI information S_(DCQB) is multiplexed with a predetermined resource for a control signal indicated by the uplink RB allocation decision information S_(USCU), and outputs it (Step S15).

The uplink RS signal generator 212 receives the uplink RB allocation decision information S_(USCU) as input, generates an uplink RS transmit signal S_(URSU) using a resource for RS predetermined in the uplink RB allocation decision information S_(USCU), and outputs it (Step S16).

The uplink data signal generator 213 receives the uplink RB allocation decision information S_(USCU) as input, generates Physical Uplink Shared Channel (PUSCH) S_(UDCU) using a resource for a data signal predetermined in the uplink RB allocation decision information S_(USCU), and outputs it (Step S17).

The multiplexer 214 receives the PUCCH S_(UCCU), uplink RS transmit signal S_(URSU), PUSCH S_(UDCU) and downlink control signal decision signal S_(DAKU) as input, and multiplexes these signals to generate a multiplexed mobile station signal S_(MUXU); the transmitter 215 transmits the mobile station transmit signal S_(MUXU) to the base station 100 (Step S18).

While the description has been made in the above-described embodiment using a configuration in which a number of frequency blocks is determined from a condition of mobile station's channel quality and an allocation resolution is set in accordance with the frequency blocks, the configuration may be one such that the allocation resolution is set in accordance with a condition of mobile station's channel quality. Moreover, in the above-described embodiment, the number of frequency blocks is described as being notified through Physical Downlink Control Channel (PDCCH), it is additionally notified with a higher-layer control signal mapped to PBCH (Physical Broadcast Channel), PDSCH (Physical Downlink Shared Channel), which is also referred to as Dynamic BCH, or the like. In this case, the number of frequency blocks S_(UDFB) is input to a PBCH generator or PDSCH generator (both not shown) provided in the downlink control signal generator 111 in the base station, and is notified to a mobile station through the PBCH or PDSCH. Furthermore, since information on the uplink and downlink control signals varies from frame to frame in aboutb 1 msec, there arises a problem that processing in a terminal becomes complicated in a case that the allocation resolution is modified with such a variation. Thus, additional limitation may be posed to modify the allocation resolution in a cycle of a plurality of frames.

Moreover, while the description has been made in the above-described embodiment using a configuration in which the allocation resolution is determined in accordance with the frequency blocks, the configuration may be one such that it is determined in accordance with a maximum number of frequency blocks, which is a maximum number of frequency blocks that can be allocated to one terminal.

Furthermore, while the description has been made in the above-described embodiment using a mode in which the uplink scheduler 104 allocates RBs with resource blocks in a number equal to the determined allocation resolution and with the determined number of frequency blocks in the embodiment, a mode may be contemplated in which RBs are allocated with resource blocks in a number equal to the determined allocation resolution and within the determined number of frequency blocks.

Moreover, while the description has been made in the above-described embodiment using a case in which the value of the allocation resolution is notified, a mode may be contemplated in which the value of the allocation resolution is not transmitted. In this case, a mobile station is configured to store a correspondence table as shown in FIG. 12, and recognize an allocation resolution using a received number of frequency blocks and the correspondence table.

The system band has been described as having 10 RBs for simplifying the explanation above; now an effect of reducing the number of bits in an actual LTE system having a system band of 20 MHz will be described. Similarly to the LTE downlink in which a plurality of frequency blocks can be allocated, on a presupposition that the number of signaling bits for use in resource allocation for one user in a system band of 20 MHz (the number of RBs=100) is 37, it is possible to hold the number of signaling bits for a number of frequency blocks of four or smaller down to 35 bits, including notification of an allocation resolution (two bits), which is less than 37 bits, by using a relationship between the number of frequency blocks and allocation resolution as in FIG. 12. FIG. 20 shows a number of bits required to notify RB patterns for frequency blocks in a number equal to the number of frequency blocks using the Tree-Based method, for numbers of frequency blocks of 1-4, respectively.

As described above, the number of frequency blocks for a mobile station with good channel quality is increased, while that for a mobile station with poor channel quality is decreased, and an allocation resolution is determined accordingly. This is because a mobile station with good channel quality performs transmission with a lower electric power density, and hence, with a broader band, and since the channel quality is good as a whole, the quality will not be degraded even when the allocation resolution is increased with the number of frequency blocks. On the other hand, a mobile station with poor channel quality performs transmission with a higher electric power density, and hence, with a narrower band, and since the channel quality is poor as a whole, the allocation resolution must be reduced with the number of frequency blocks in order to accurately select better resources from among all. Thus, by correlating the allocation resolution, number of frequency blocks and channel quality of a mobile station with one another, degradation in reception property due to setting of an allocation resolution may be reduced.

While a mode in which uplink resource blocks are allocated has been described in the embodiments above, the mode may be one such that downlink resource blocks are allocated. In such a case, the number of frequency blocks or maximum number of frequency blocks may be information varying in accordance with a communication environment, such as, for example, the cell size, system bandwidth, coverage of a base station, channel quality information measured by a downlink reference signal, bandwidth of downlink data signals, and number of levels in multi-level modulation for downlink data signals, or code rate. Moreover, since the aforementioned cell size is determined by information affecting the communication environment such as the position of a base station, distance between base stations, and interference power, the number of frequency blocks may be selected using such information.

Furthermore, a mode in which the mode of allocating uplink resource blocks is combined for execution with the mode of allocating downlink resource blocks may be contemplated.

In addition, while it is possible to configure the mobile station and the base station in the present invention described above by hardware, they may be implemented by a computer program as obvious from the preceding description.

A processor operated by programs stored in a program memory implements functions and operations similar to those in the embodiments described above. It should be noted that part of functions of the embodiments described above may be implemented by a computer program.

While the present invention has been described with reference to several embodiments, it is not limited thereto. Various modifications that those skilled in the art can appreciate may be made to the configuration or details of the present invention within a scope of the present invention.

The present application claims priority based on Japanese Patent Application No. 2008-161753 filed on Jun. 20, 2008, disclosure of which is incorporated herein in its entirety. 

1. A resource allocation method comprising: allocating resource block groups including at least one or more resource blocks consecutive on a frequency axis to a terminal; and determining a number of control signals for notifying allocation information representing resource blocks in said allocated resource block groups.
 2. A resource allocation method according to claim 1, comprising determining the number of said control signals to be equal to a number of the allocated resource block groups.
 3. A resource allocation method according to claim 1, comprising notifying allocation information for a plurality of resource block groups through one control signal, and determining the number of said control signals to be less than a number of the allocated resource block groups.
 4. A resource allocation method according to claim 1, comprising determining the number of said control signals to be equal to a maximum number of resource block groups that can be allocated to a terminal.
 5. A resource allocation method according to claim 1, comprising notifying allocation information for a plurality of resource block groups through one control signal, and determining the number of said control signals to be less than a maximum number of resource block groups that can be allocated to a terminal.
 6. A resource allocation method according to claim 1, comprising modifying a size of said control signal in accordance with a size of the allocation information.
 7. A resource allocation method according to claim 1, comprising allocating resource blocks in a determined unit of resource block allocation, when allocating the resource block groups.
 8. A resource allocation method according to claim 7, comprising determining a unit of resource block allocation in accordance with a maximum number of resource block groups that can be allocated to a terminal.
 9. A resource allocation method according to claim 7, comprising determining a unit of resource block allocation in accordance with a number of resource block groups.
 10. A resource allocation method according to claim 7, comprising determining a unit of resource block allocation based on information about a communication environment of a base station or a mobile station, information affecting the communication environment, or communication capability.
 11. A resource allocation method according to claim 7, comprising determining a structure in a Tree-Based method in order to represent resource blocks allocated with the determined unit of resource block allocation in the Tree-Based method.
 12. A resource allocation method according to claim 11, comprising modifying a number of bits of information representing the allocated resource blocks in accordance with a structure in the Tree-Based method.
 13. A resource allocation method according to claim 7, comprising modifying a size of the control signal in accordance with a unit of allocation.
 14. A resource allocation method according to claim 7, comprising modifying a number of pieces of allocation information to be notified through one control signal in accordance with a unit of allocation.
 15. A resource allocation method according to claim 7, comprising notifying, to a terminal, scheduling information having information representing the allocated resource blocks and information on the unit of allocation.
 16. A resource allocation method according to claim 15, comprising discriminating a structure in a Tree-Based method from information about the unit of allocation in the transmitted scheduling information to identify allocated resource blocks indicated in the scheduling information.
 17. A resource allocation method according to claim 1, comprising notifying, to a terminal, information representing the allocated resource blocks, and a number of allocated resource block groups or a maximum number of resource block groups that can be allocated to the terminal.
 18. A resource allocation method according to claim 17, comprising discriminating a structure in a Tree-Based method based on a transmitted number of resource block groups or a maximum number of resource block groups to identify allocated resource blocks indicated in the information representing allocated resource blocks.
 19. A communication method of allocating resource block groups including at least one or more resource blocks consecutive on a frequency axis, comprising: identifying resource blocks allocated to a mobile station from information on allocated resource block groups notified using a determined number of control signals.
 20. A wireless system comprising: allocator for allocating resource block groups including at least one or more resource blocks consecutive on a frequency axis to a terminal; and determiner for determining a number of control signals for notifying allocation information representing resource blocks in said allocated resource block groups.
 21. A wireless system according to claim 20, wherein said determiner determines the number of said control signals to be equal to a number of the allocated resource block groups.
 22. A wireless system according to claim 20, wherein said determiner determines the number of said control signals to be less than a number of the allocated resource block groups, when notifying allocation information for a plurality of resource block groups through one control signal.
 23. A wireless system according to claim 20, wherein said determiner determines the number of said control signals to be equal to a maximum number of resource block groups that can be allocated to a terminal.
 24. A wireless system according to claim 20, wherein said determiner notifies allocation information for a plurality of resource block groups through one control signal, and determines the number of said control signals to be less than a maximum number of resource block groups that can be allocated to a terminal.
 25. A wireless system according to claim 20, comprising notifier for notifying to a terminal the allocation information, and a number of allocated resource block groups or a maximum number of resource block groups that can be allocated to a terminal.
 26. A wireless system according to claim 20, comprising control signal generator for modifying a size of said control signal in accordance with a size of the allocation information.
 27. A wireless system according to claim 20, wherein said allocator allocates resource blocks in a unit of resource block allocation determined in allocating at least one or more resource block groups.
 28. A wireless system according to claim 27, wherein said control signal generator modifies a size of said control signal in accordance with said unit of allocation.
 29. A wireless system according to claim 27, wherein said control signal generator modifies a number of pieces of allocation information to be notified through one control signal in accordance with said unit of allocation.
 30. A wireless system for allocating resource block groups including at least one or more resource blocks consecutive on a frequency axis, comprising: identifier for identifying resource blocks allocated to a mobile station from information on allocated resource block groups notified using a determined number of control signals.
 31. A base station comprising: allocator for allocating resource block groups including at least one or more resource blocks consecutive on a frequency axis to a terminal; and determiner for determining a number of control signals for notifying allocation information representing resource blocks in said allocated resource block groups.
 32. A base station according to claim 31, wherein said determiner determines the number of said control signals to be equal to a number of the allocated resource block groups.
 33. A base station according to claim 31, wherein said determiner determines the number of said control signals to be less than the number of the allocated resource block groups, when notifying allocation information for a plurality of resource block groups through one control signal.
 34. A base station according to claim 31, wherein said determiner determines the number of said control signals to be equal to a maximum number of resource block groups that can be allocated to a terminal.
 35. A base station according to claim 31, wherein said determiner determines the number of said control signals to be less than a maximum number of resource block groups that can be allocated to a terminal, when notifying allocation information for a plurality of resource block groups through one control signal.
 36. A base station according to claim 31, comprising notifier for notifying to a terminal the allocation information, and a number of allocated resource block groups or a maximum number of resource block groups that can be allocated to a terminal.
 37. A base station according to claim 31, comprising control signal generator for modifying a size of said control signal in accordance with a size of the allocation information.
 38. A base station according to claim 31, wherein said allocator allocates resource blocks in a unit of resource block allocation determined in allocating at least one or more resource block groups.
 39. A base station according to claim 38, wherein said control signal generator modifies a size of said control signal in accordance with a unit of allocation.
 40. A base station according to claim 38, wherein said control signal generator modifies a number of pieces of allocation information to be notified through one control signal in accordance with a unit of allocation.
 41. A mobile station for identifying allocation of resource block groups including at least one or more resource blocks consecutive on a frequency axis, comprising: identifier for identifying resource blocks allocated to the mobile station from information on allocated resource block groups notified using a determined number of control signals.
 42. A program for a base station, said program causing said base station to execute: allocating processing of allocating resource block groups including at least one or more resource blocks consecutive on a frequency axis to a terminal; and determining processing of determining a number of control signals for notifying allocation information representing resource blocks in said allocated resource block groups.
 43. A program for a mobile station for identifying allocation of resource block groups including at least one or more resource blocks consecutive on a frequency axis, said program causing said mobile station to execute: identifying processing of identifying resource blocks allocated to the mobile station from information on allocated resource block groups notified using a determined number of control signals. 